1. Field of the Invention
The disclosed technology relates to a plasma processing apparatus and a semiconductor device manufactured by the same apparatus. More particularly, the disclosed technology relates to a plasma processing apparatus which is for use in manufacturing a semiconductor device by plasma discharge of reactive material gas in a sealable chamber, for example, by processing a substrate which is a material to be processed, and in which a plurality of sets of cathode-anode bodies for performing plasma discharge are provided in the chamber so that a plurality of discharge spaces exist, and also relates to a semiconductor device manufactured by this plasma processing apparatus.
2. Description of the Related Art
A vertical type plasma processing apparatus shown in FIG. 5 is known in the conventional art as a semiconductor device manufacturing apparatus which is a kind of a general plasma processing apparatus.
The semiconductor device manufacturing apparatus shown in FIG. 5 comprises a sealable vertical type chamber 11 as a reactive vessel, and anodes 4, 4 are substantially vertically arranged with respect to a bottom surface of the chamber 11 at its inside center portion. Each of the anodes 4, 4 comes in contact with a heater 14 substantially vertically arranged with respect to the bottom surface of the chamber 11 at its center portion. The heater 14 serves to heat a glass substrate 1 (held by a substrate holding part 15), which is a material to be processed, at a constant temperature, for example, 100° C. to 600° C. The semiconductor device manufacturing apparatus further comprises cathodes 2, 2 which are substantially vertically arranged with respect to the bottom surface of the chamber 11 near the side wall of the inside of the chamber 11.
The semiconductor device manufacturing apparatus will be more specifically described. That is, the anodes 4, 4 and the cathodes 2, 2 are arranged so that the anodes 4, 4 are sandwiched by the cathodes 2, 2 (in a state where two sets of the cathode and anodes are placed opposite) with a predetermined interval in a horizontal direction. Then, plasma discharge is performed at spaces between each of the anodes 4 and each of the cathodes 2 with reactive material gas introduced into the chamber 11.
The chamber 11 and the anodes 4, 4 use material such as stainless steel or aluminum alloy and use ceramics or the like for thermal insulation. Each cathode 2 is arranged so as to face the substrate 1 with a predetermined interval. Furthermore, each cathode 2 is supported by a cathode support 5 made of insulating glass in order to obtain electrical insulation. The heater 14 is grounded via a grounding terminal 20.
It is general that a gas introduction pipe 10 is arranged in a branched manner within a space in a housing where exhaust ventilation is performed outside the chamber 11 in order to evenly supply material gas to a plurality of discharge spaces in the semiconductor device manufacturing apparatus. Furthermore, it is also general that conductance is adjusted by providing a needle valve in each gas introduction pipe 10 after branching in order to improve difference in conductance caused by difference in piping length.
Further, a plurality of gas introduction pipes 10 are arranged by stainless steel pipes with high airtightness between the gas supply source and the chamber 11 and connected to ports located adjacent to individual discharge spaces. Consequently, in the case where gas is introduced to the cathode 2, since insulation needs to be provided between the stainless steel pipe which introduces gas and the cathode, it is required to connect by sandwiching an expensive insulating insulator. Then, gas to be introduced into the discharge space is introduced into the inside of the chamber 11 via the plurality of stainless steel pipes 10. A pressure controller 22 and a vacuum pump 21 are provided in order to flexibly control pressure of reactive gas in the chamber. A toxic substance elimination device 23 is connected to the vacuum pump 21 in order to eliminate toxic substance in exhaust gas.
In addition, as for a conventional plasma processing apparatus, those which improve etching or evaporation uniformity in a plasma chemical technology are known (see, for example, U.S. Pat. No. 4,264,393).
In an apparatus disclosed in U.S. Pat. No. 4,264,393, the number of a gas introduction pipe from a gas supply source to a chamber is one; however, the gas introduction pipe is branched into a plurality of gas introduction pipes which are the same as the number of discharge spaces in the chamber in order to supply gas to the plurality of discharge spaces in the chamber.
The aforementioned conventional plasma processing apparatuses have the following problems.
First, the apparatus shown in FIG. 5 will be described. In this apparatus, the gas introduction pipe 10 is branched within a space in a housing where exhaust ventilation is performed outside the chamber 11. Furthermore, it is also required that a needle valve in each gas introduction pipe 10 after branching is provided for the purpose of improving difference in conductance caused by difference in piping length; therefore, it naturally becomes high cost.
Further, since the plurality of gas introduction pipes 10 are arranged by stainless steel pipes with high airtightness between the gas supply source and the chamber 11 and connected to ports located adjacent to individual discharge spaces, their piping lengths are not less than a plurality of times the distance from the gas supply source to the chamber 11.
The gas introduction pipe 10 is required to use stainless steel pipe with high airtightness because gas to be introduced to the discharge space is accompanied with high danger when gas such as special high pressure gas or hydrogen leaks and the port is required to provide the number corresponding to those of the discharge spaces, resulting in further high cost. Furthermore, since the entire distance of the gas introduction system is long compared to the case where simple connection is made with a single pipe and the number of valves is many, delicate consideration is required for safety of exhaust ventilation at the branch section, and consequently it becomes a serious cost.
Further, in the case where gas is introduced to the cathode 2, since insulation needs to be provided between the stainless steel pipe which introduces gas to the individual discharge spaces and the cathode, it is required to connect by sandwiching an expensive insulating insulator, resulting in high cost. Furthermore, since there is no material having considerably high heat resistance in processable insulating components, in the case where temperature of the cathode 2 becomes approximately 180° C. or more, a water cooling pipe is required for the purpose of cooling this part, and consequently it becomes a serious cost.
Next, the apparatus disclosed in U.S. Pat. No. 4,264,393 will be described. In this apparatus, the number of the gas introduction pipe from the gas supply source to the chamber is one; however, the gas introduction pipe is branched into a plurality of gas introduction pipes which are the same as the number of discharge spaces in order to supply gas to the plurality of discharge spaces in the chamber. This can reduce cost of piping outside the chamber.
However, in the case where gas is simultaneously supplied to a plurality of discharge spaces, when piping lengths for introducing gas are largely different as shown in the drawing, the gas cannot be equally introduced into the respective discharge spaces. If the gas is evenly introduced into the respective discharge spaces with this configuration, a needle valve needs to be provided in each gas introduction pipe after branching as in the apparatus shown in FIG. 5, and consequently it becomes a serious cost.